Tuesday, May 3, 2011

Intro to Studio Strobes

Lately I've been thinking about doing more setup shots, especially location shots.  Outdoors you usually need more power because of the much brighter ambient conditions, especially with the days getting longer (at least in the northern hemisphere).  In terms of capacity to overpower the sun (even with a large modifier), a studio strobe is much more powerful than hotshoe flashes.  If you don't know anything about strobes, this post is for you.
BTW, strobes can mean different things to people.  I use the term to refer to big flashes.  First, I'll discuss their advantages and disadvantages compared to hotshoe flashes.  Next I'll talk about the main types of strobes.  I'll then discuss the strobe that I'd like to get, then finally I'll talk about remote adjustment options.

+ Strobes are far more powerful than hotshoe flashes.  An Alien Bee B1600 for example, is approximately equivalent to ten SB-800s or about twenty SB-700s.  On the other hand, sometimes they are too powerful (such as when you want to use a wide aperture to get shallow depth of field).
+ Unlike hotshoe flashes whose flash tubes are recessed in the flash head, strobes have flash tubes that stick out, allowing the light to spread out in all directions, which makes them more suitable for modifiers such as softboxes -- no tupperware needed either. :) 
+ Many strobes also offer modeling lights (i.e., continuous lights that allow you to get a better idea of what the flash will look like).  My SB-800 does have a modeling light but it's pretty weak and pulses like a disco strobe light.
+ Fast recycling time.  An external battery pack for a hotshoe flash can mitigate this advantage somewhat but strobes can fire off shots quickly and take longer to overheat.
On the other hand:
- strobes are generally larger, and they need either an AC power outlet or a separate battery pack (battery-powered strobes being somewhat of an exception). 
- Their upfront cost is also much higher than speedlights although if you try to amass speedlights with equivalent power, using strobes can be more cost-effective. 
- Most strobes can only be used in manual mode (although some battery-powered strobes can operate in TTL mode).  
- No high speed sync (with a few exceptions).
- No zooming.  If you want to change the shape of the beam, you have to change the reflector or modifier.
- Finally, speedlights can have a shorter flash duration than some monolights (again, there are exceptions).  Many monolights also have a longer flash duration when you use less power.

The power of a hotshoe flash is usually expressed as a Guide Number, whereas the power of a strobe is usually measured in watt-seconds.  Watt-seconds don't convert into guide number because watt-seconds just describe the raw power and says nothing about efficiency and coverage (a large reflector can have a focusing effect like zooming the flash head).  That said, a Nikon SB-800 or Canon 580EXII has about 60 watt-seconds, while a medium-powered monolight like the Alien Bees B800 has 320 watt-seconds of power, and there are strobes with 640 watt-seconds, 1320 watt-seconds, and higher.

There are three main types of strobes: monolights, studio packs, and battery-powered strobes.
  • Monolights (aka monoblocs) have both a flash head and power supply built into the body of the flash.  The body is then connected to a power outlet or to a battery pack.  It is triggered either by a sync cord connected to the camera, an optical slave, or a radio trigger.  Generally, you set the power manually on the monolight itself, although there are options for remote adjustment (discussed below).  Examples include: Alien Bees, Hensel Integra, Elinchrom D-Lite.
  • Studio packs (aka "pack and head" or generator) have one or more flash heads connected via cords to a central power supply.  You can set the power level of the flash on the power supply (the better models allow power to be set independently for each flash).  The power supply is then connected to a power outlet or a battery pack.  The advantages of a studio pack compared to a monolight are: the convenience of setting power from the power supply, and lighter flash heads (more stable on light stands) .  The disadvantage is that if the flash heads are positioned far from each other, then they will likely need separate power supplies.  Another disadvantage of studio packs is that if the power supply fails, you won't be able to use any of the flashes.  Finally, studio packs tend to be more expensive than monolights.  Examples include: Broncolor Pulso and Grafit, Profoto AcuteB2 system (here).
  • Battery powered strobes are somewhat like studio packs, except that they connect to a battery pack and are designed to be fairly portable (though not as portable as hotshoe flashes).  Some of them have power that's controlled by the head (like a monolight), while others have power controlled by the battery pack (like a studio pack). Examples include: Quantum Qflashes, Elinchrom Ranger RX, Elinchrom Quadra RX, Norman A200C and A400B.

Strobes can be quite expensive.  One of the less expensive strobe brands out there that nonetheless has a decent reputation for quality is Paul C. Buff, Inc.  PCB makes three lines of monoblocs:
Alien Bees are PCB's entry level flash units.  They have most of the features I care about, such as a cooling fan, auto-dump (to drain excess charge automatically), reasonable availability of flash modifiers, stepless adjustment down to 1/32 power, good triggering options (see below), and excellent customer support, all at the right price.
A step above Alien Bees are the White Lightning flash units.  They're built a little sturdier with aluminum instead of plastic bodies.  In addition, the X1600 and X3200 have a switch that can deactivate some of the capacitors, reducing the power to 1/4th without slowing down the flash duration.
The newest PCB flash unit is the Einstein, which has a lot of cutting edge features:
  • The Einstein uses IGBT transistors.  What that means is that unlike analog strobes, the flash duration of the Einstein becomes shorter when you decrease its power (just like hotshoe flashes).   The Einstein can be used in action mode (for faster flash duration) with t.1 durations as short as 1/13,500. 
  • Alien Bees have been criticized for inconsistent color at low power.  That's remedied by the Einstein's Color mode, which uses digital technology to give the same color temperature at any power level.
  • power adjustment in 1/10th stop increments over a range of 9-stops (down to 2.5ws).
  • More powerful modeling light.

Within the last year or so, remote adjustment options for studio strobes, particularly the PCB strobes have increased.

Alien Bees and White Lightning:
Alien Bees and White Lightning strobes can be triggered by radio using the cheap ebay triggers.  However, they also feature an RJ-11 jack (just like landline phones), which allows them to be adjusted remotely in several ways:
- by wired connection via an LG4X 4-Channel Wired Remote.
- wireless radio via Cyber Commander™.  The Cyber Commander is pretty cool system for controlling strobes.  The Cyber Commander can control up to 16 lights and has a built-in flashmeter (!) that can tell you the f/stop of each light or any group of lights.  And if you have an unlimited sync speed camera such as the Nikon D70, the Cyber Commander system will allow sync speeds of up to 1/2500.  A Cyber Commander can also trigger a speedlight but not remotely adjust it (darn!).
- wireless radio via the Radiopopper JrX Studio receiver, and have their power adjusted remotely from the camera's position with either a Radiopopper JrX Studio transmitter or a PX transmitter. An important advantage of the Radiopoppers is that they can also control hotshoe flashes, making it possible to combine both hotshoe flashes and these strobes, all remotely adjusted.
- wireless radio via PocketWizard AC9 receiver, with the power adjusted remotely either by a PocketWizard MiniTT1 or a FlexTT5.  As with the Radiopopper system, this makes it possible to combine hotshoe flashes with these strobes, with remote adjustment capability.

The Einstein has different triggering options because it's digital, unlike the Alien Bee and White Lightning strobes.
-  wireless radio via Cyber Commander.  What's cool is that the dedicated receiver for Einsteins, the CSXCV*, costs just $30!  *PCB needs a marketing consultant to rename their products...
- wireless radio via PocketWizard PowerMC2 receiver, with the power adjusted remotely either by a PocketWizard MiniTT1 or a FlexTT5.
- as of now, there is no Radiopopper unit yet that can remotely adjust the Einstein.

I'm still debating whether to go with an Alien Bee or Einstein, though I'm leaning toward the latter.  Meanwhile, I'd like to use a multiple speedlight setup first, which I will be discussing next.

  1. Multiple Speedlights vs. Studio Strobe.
  2. Are you ready for AlienBees?
Syl Arena's Speedliter's Handbook
Strobist.com - A Walk Around the Monobloc
Photo.net - Intro to Studio Lighting Equipment